HK1104753B - Point to multi-point services using high speed shared channels in wireless communication systems - Google Patents

Description

Point-to-multipoint service using high speed shared channel in wireless communication system

This application is a divisional application of a patent application entitled "point-to-multipoint service using high speed shared channel in wireless communication system" filed 30.4.2004 with application number 03809802.4.

Technical Field

The present invention relates generally to wireless communication systems, and more particularly to point-to-multipoint services in such systems.

Background

There is an increasing desire to use point-to-multipoint services in wireless communication systems, as shown in figure 1, where a service is sent from a single point, such as a base station, to multiple points, such as user equipment. Examples of point-to-multipoint services are multimedia broadcast and multicast services.

In the system proposed by the third generation partnership project (3GPP), one proposed channel that can be used for this service is the Forward Access Channel (FACH). The FACH is a downlink common transport channel (TrCH) that can be received by all users. The FACH TrCH is propagated by applying it to a secondary common control physical channel (S-CCPCH). The S-CCPCH is transmitted to all cell users.

To limit the radio resources allocated to the S-CCPCH, the S-CCPCH data rate is limited. To illustrate, if a high data rate service is transmitted on the S-CCPCH, then it is necessary to transmit using low data redundancy to achieve the high data rate. Since the S-CCPCH is transmitted to the entire cell, it is transmitted at a power level around the cell sufficient for reception by users at the desired quality of service (QOS). Propagating high data rate services at this power level increases the interface to other users, reducing system capacity, which is highly undesirable.

Due to the nature of the propagation of the S-CCPCH and FACH, the radio resources required for the S-CCPCH and FACH are very static. The Modulation and Coding Set (MCS) and transmit power level used by the S-CCPCH needs to be sufficient to maintain the desired QOS around the cell.

One shared channel proposed for use in 3GPP systems is the high speed downlink shared channel (HS-DSCH). The HS-DSCHs are high speed channels that are time shared by cell users (user equipments). Each transmission is targeted to a respective user and the transmissions of each user on the HS-DSCH are separated by time.

The HS-DSCH transmission to a user is accompanied by uplink and downlink dedicated control channels. Each user transmits measurements via layer 1 and layer 3 signaling signals (signaling) on the uplink control channel, using which a Modulation and Coding Set (MCS) is selected for the user's transmission. The MCS may change every 2 to 10 milliseconds. By carefully selecting the MCS for user transmissions, the least robust (lowest data redundancy) MCS may be selected to maintain a desired quality of service (QOS). As a result, radio resources are more efficiently utilized.

To determine when a particular user's transmission can be transmitted on the HS-DSCH, the user first looks for its UE ID encoded in a Cyclic Redundancy Code (CRC) on the downlink control channel set and decodes the downlink control channel to obtain HS-DSCH allocation data. After a predetermined period, the UE receives the HS-DSCH to obtain a packet with its UE ID and decodes the packet to receive user data.

Although the HS-DSCH allows for a more efficient use of radio resources, only point-to-point services can be handled by the HS-DSCH. To handle multiple reception points, multiple transmissions must be made on the HS-DSCH. Such multiple transmissions use a large amount of radio resources, which is undesirable.

Therefore, it is desirable to have a flexible mechanism to provide point-to-multipoint services.

Disclosure of Invention

Service data is transmitted in a wireless communication system, and a first service identification is transmitted for reception by a group of users in a cell of the system, the group of users not including all users of the cell. Each of the group of users receives the service identification. Each of the group of users monitors a second service identification transmitted on a high speed downlink shared channel (HS-DSCH). The service data is transmitted on the HS-DSCH with a second service identity. Each of the group of users detects a second service identification and receives service data of the HS-DSCH.

Drawings

Fig. 1 is an illustration of a point-to-multipoint service.

Figure 2 is an illustration of a preferred HS-DSCH and associated control channels.

Fig. 3 is a simplified diagram of a preferred node B and user equipment.

Fig. 4 is a simplified diagram of a preferred node B with a preferred scheduling mechanism for the HS-DSCH.

Fig. 5A and 5B are illustrations of preferred HS-DSCH signals for the HS-DSCH.

Fig. 6 is an illustration of the establishment and transmission of preferred signals for point-to-multipoint services on the HS-DSCH.

Fig. 7 is an illustration of channel mapping for point-to-multipoint services on the HS-DSCH performed by a radio network controller and user equipment.

Detailed Description

Although the preferred embodiments are described in terms of preferred 3GPP proposed systems, they may be used with other radio systems that use point-to-multipoint transmissions.

Fig. 2 is an illustration of a preferred HS-DSCH16 and its associated downlink control channel 13 for transmission of point-to-multipoint (PtM) services. In FIG. 2, a group of user UEs 112₁、...、UE J 12_J、...、UE N 12_NTo receive the service on the HS-DSCH 16. A downlink Common Control Channel (CCC)13 is used to allocate the HS-DSCH16 to the user UE 112₁、...、UE J 12_J、...、UE N12_N. The HS-DSCH16 is sent by the base station 10 and by the UEs 12₁-12_NAnd receiving the group. UEs as UEX12 not logged into this service_xDoes not conform to the service identification code on the CCC 13. Thus, this UE, UEX12_xNot configured to receive data for the HS-DSCH 16.

FIG. 3 illustrates one of the node Bs 18 and UEs, UE J12_JFor a simplified illustration of the data transmitted on the HS-DSCH 16. At the node-B18, a downlink control channel generator 24 generates each UE12₁-12_NThe CCC signal of (c). For UE J12_JAfter the CCC 13 is radiated by the antenna 32 or antenna array through the radio interface 22, the signal is transmitted by the UE J12_JAntenna 34 or antennaThe line array receives and is processed by the CCC receiver 36 to recover the control data for the channel, such as the modulation and coding set for the HS-DSCH 16.

An HS-DSCH generator 26 generates the HS-DSCH signals for transmission over the radio interface 22. The HS-DSCH signal is transmitted by UE J12 using its antenna 34 or antenna array_JAnd receiving. The data of the HS-DSCH16 is recovered using the CCC data by an HS-DSCH receiver 38, a channel quality measurement device 40 picks up channel quality measurements/data of the HS-DSCH, such as signal-to-noise ratio (SIR) or block error rate (BLER). Channel quality may also be derived from the downlink supplemental dedicated channel. The measurements/data are transmitted to the node-B18 by an uplink physical control channel (CCC) transmitter, or by layer 3 signaling steps.

In addition, an automatic reply request (ARQ) transmitter 41 at the user equipment 12 transmits Acknowledgement (ACKs) and negative ACKs (naks) indicating whether the HS-DSCH data has been successfully received. An ARQ receiver 31 at the node B18 receives the ACKs and NAKs, and if a NAK is received by any of the HS-DSCH transmitting users, the HS-DSCH transmission is typically repeated, and the node B18 checks the ACKs/NAKs for all users. Typically, if any user transmits a NAK, retransmission is performed. However, if there are only some NAKs that exceed a threshold, retransmission is only encouraged. Typically, a time limit for retransmissions is set, preferably, the UEs 12ACKing ignore subsequent retransmissions, saving their power.

A cqi processor 30 at the node B18 replies with the cqi/data from all users of the HS-DSCH. A Modulation and Coding Set (MCS) selection device 28 uses the channel measurements/data from each user that has logged in to receive the PtM service (user group) to select an MCS for the HS-DSCH transmission. Preferably, the MCS selected is the least robust (highest data rate) so that the channel conditions allow the user in this PtM user group with the worst received measured HS-DSCH signal quality to operate. Preferably, the MCS is updated every Transmission Time Interval (TTI), although a longer time frame may be used. The CCC generator 24 generates the CCC, which is displayed to UE 112₁、...、UE J 12_J、...、UE N 12_NTo perform appropriate reception of the HS-DSCH. The HS-DSCH generator 26 generates the HS-DSCH16 using the selected MCS.

For services with multiple sub-streams, the transmission characteristics of the various sub-streams may be handled individually. For illustrative purposes, multimedia services may have audio, video, and text sub-streams. The QOS of each sub-stream may be different such that different transport attributes may be used by each sub-stream. This approach may result in better resource efficiency, and each sub-stream may be processed individually rather than transmitting each sub-stream to meet the highest QOS sub-stream requirements. For each sub-stream, the block error rate (BLER) is compared to a BLER quality target.

Fig. 4 is a simplified block diagram of a preferred scheduling mechanism for the node B18. The scheduling mechanism 46 is preferably used to schedule data for each TTI, although longer scheduling times may be used. The scheduling mechanism 46 receives point-to-point (PtP) and PtM data to be transmitted over the HS-DSCH. The scheduler determines which user receives the PtP transmission and which user group receives the PtM transmission in the next TTI.

Scheduling data transmission during the preferred time period results in more efficient utilization of the voice resources. To illustrate, a small amount of data may be used for dedicated PtP transmissions in a particular TTI, and the scheduling mechanism 46 may increase the amount of PtM data transmitted over the HS-DSCH channel due to the increased availability of voice resources over that TTI. Similarly, the scheduler 46 may select to transmit PtP services when PtM data is not provided. Another scheduling criterion is QoS attributes, such as transmission delay and/or data throughput requirements for PtP or PtM services. Scheduling on a TTI basis provides greater ability to meet these requirements while maintaining high utilization of HS-DSCH cell resources.

The scheduler 46 may also take into account physical transmission requirements. For example, one user or group of users may require a more robust MCS than another. During the next TTI, resources may only be provided to the less robust MCS, and then the scheduler 46 reschedules the transmission of PtP users or PtM user groups to maximize the use of the provided resources. The ability to schedule within this interval improves the number of satisfied users and the overall utilization and efficient use of physical resources since the data provided for transmission has specific QOS requirements and the physical resources and channel quality measurements provided vary based on the TTI reference.

The scheduler 46 also gets ACK/NAK feedback from all users of the PtM user group and schedules retransmission until all users indicate successful reception of the transmission by sending an ACK, or some limit is reached, or a service transmission time limit is reached or a retransmission limit is reached. The advantage of this approach is that only part of the erroneous PtM service is retransmitted, rather than retransmitting the entire service transmission. Preferably, any retransmissions are ignored by the user that previously generated the ACK.

An advantage of this approach is the ability to dynamically schedule between PtP and PtM services based on the TT1 reference rather than scheduling S-CCPCHs in layer 3 steps, which require 100 more milliseconds to several seconds in size for channel allocation, which provides improved QOS and physical resource management. In addition, it allows the UE to receive multiple services without having the capacity for simultaneous channel reception, since overlapping physical allocations can be avoided, such multiple services can be separated by time.

The node-B18 signals the UEs 12 on the CCC 13₁-12_NChannel configuration is UE12₁-12_NData may be transmitted. The preferred scheduling per TTI reduces resource conflicts between services by maximizing the use of radio resources, which channel allocation signals to users via the downlink CCC use signaling device 48. Without the mechanism 46, channels cannot generally be reallocated over TTIs and as a result the ability to maintain QOS and high utilization and efficient use of physical resources is limited.

Fig. 5A and 5B are illustrations of the preferred HS-DSCH signaling for the HS-DSCH 16. In FIG. 5A, each UE12 of the PtM subscriber group detects the PtM service ID 51 associated with all the subscribers₁-12_NIs informed of the service delivery. The service ID 51 is encoded on the downlink common control channel 13. After a predetermined time period, the user receives the HS-DSCH for the authorized service.

In FIG. 5B, UE group ID 153 is detected by detecting companion UEs₁To UE group ID N53_NEach UE12₁-12_NIs informed of the service delivery, which is encoded in the downlink common control channel 13. After a predetermined time period, the user receives the HS-DSCH16 displayed by the CCC 13 for packets with the service ID of the authorized service.

Fig. 6 is an illustration of preferred signals for establishing and transmitting point-to-multipoint services over HS-DSCHs. The RAN 70 signals each user to receive the service for the delivery attribute of the transmission 74. Each user configures itself to receive the transmission and to monitor the CCC for PtM service ID groups, 72. Data for a point-to-multipoint service is transmitted and received from the core network by the UMTS radio access network (UTRAN) 70. The service/group/UE ID on the CCC indicates that after a specified time period, the HS-DSCH transmission will soon occur on a specific HS-DSCH physical channel, after receiving the CCC, each user configures itself to receive the HS-DSCH transmission.

Each user may send channel quality data to the RAN 70, 76 in layer 3 signaling steps. The channel data may also be reported on a TTI basis by physical layer signaling, 78. Using the channel quality data for all users in each PtM user group, the RAN 70 determines an appropriate MCS for HS-DSCH transmissions to each PtM user group. For illustrative purposes, the RAN 70 typically sets the MCS at a level that is acceptable at the desired QOS by the user with the worst reception quality. To optimize the use of radio resources, it is preferred that these parameters are updated every Time Transmission Interval (TTI), although a longer time range may be used between updates.

The UTRAN 70 simultaneously performs the HS-DSCH allocation, 82, and each UE12 configures the HS-DSCH reception, 84. Service data is transmitted on the HS-DSCH, 86. The service data transmitted on the HS-DSCH is received by the UE 12. After authentication, the service data is forwarded to the common traffic channel, and preferred configurations allow flexibility in transferring common traffic channel data over shared or dedicated channels such as PtM or PtP transmissions. This mapping is performed on both the transmit side and the receive side of the wireless interface.

Fig. 7 is an illustration of a preferred channel mapping at the ratio of the radio network controller 19 to the UE 12. The PtM data arrives at the RNC on a common communication channel (CTCH) which is mapped on the HS-DSCH for transmission to the user on the physical channel (HS-PDSCH). One UE12 is illustrated herein and typically multiple UEs receive the HS-DSCH transmission. The UE12 receives the HS-PDSCH and maps the HS-DSCH to the CTCH for processing by the UE 12.

Claims (5)

1. A node B, comprising:

an input configured to receive point-to-point (PtP) and point-to-multipoint (PtM) data;

scheduling means for receiving received data and scheduling the data for PtP and PtM transmission, the PtM transmission being transmitted over a high speed shared channel, wherein the data is intended for users having a predetermined service identity, and said users do not include all multiple users to which the high speed shared channel simultaneously transmits data; and

and the transmitting device is used for transmitting the data scheduling to the user with the preset service identification code.

2. The node B of claim 1 wherein said scheduling is based on a data delay and data throughput requirements of said received data.

3. The node B of claim 1, wherein the scheduling is performed on a tti reference.

4. The node-B of claim 1 wherein said scheduling is based on a robustness of the PtP and PtM transmissions.

5. The node-B of claim 1 wherein the scheduling of the retransmission of the PtM data is based on received acknowledgements and negative acknowledgements of all users that intend to receive the PtM data.